1. Field of the Invention
The present invention is directed to a fastening system for a mucous membrane-supported denture composed of ball or spherical heads fastened from implants or natural teeth. The size of the head is greater than a hemisphere and the surface is highly polished surface. The head secures the denture and engages the retaining caps provided in recesses of the denture which are composed of smooth and elastic plastic material.
2. Field of the Invention
Dentures which adhere by means of suction action on the palate or which are supported by means of gripping elements on the remainder of the tooth are known. These dentures can be designated as mucous membrane-supported dentures. The latter are often unsatisfactorily supported and loosen during the intake of food and when talking. Therefore, the fastening of an artificial tooth substitute on enossal implants inserted in the ridge of the jaw has been suggested. This technique is widespread in dentistry but cannot be applied successfully in every case. Rather, it is substantially restricted to providing a secure support to individual tooth substitutes which cannot be removed or to abridged rows of teeth and is employed for this purpose with some success.
Patent CH No. 597,843 discloses a system for fastening a mucous membrane-supported denture in which a denture, having a retaining cap made of an elastic material attached, is fastened on implants carrying spherical heads. The retaining caps encircle or encase the spherical heads almost completely, thereby producing a rigid fastening of the snap fastener type. However, this system is disadvantageous because a lateral movement of the denture is not possible due to the rigidity of the support.
Patent FR No. 12 11 044 discloses the fastening of spheres or cylinders made of rust free, non-magnetic metals or alloys on screw-shaped implants. The suggested cylindrical form provides for a ball cap on the end by which the cylinder is fastened on the implant. Correspondingly formed matching pieces, so-called male molds, are provided for fastening on the spheres or cylinders. The matching pieces are welded together by means of metal bands, resulting in a rigid connection to produce a removable bridge. Special rod-like pieces fastened to the matching pieces are slid over the spheres or cylinders or the end plate of the matching piece serve for the fastening of the tooth substitute. A disadvantage in this system is that the forces occurring during chewing are transmitted directly to the sphere head or the implant as a consequence of the rigid connection. A further suggestion in FR No. 12 11 044 provides for an elastic substance arranged in the matching pieces. However, this embodiment is also disadvantageous since a lateral movement of the tooth substitute is not possible due to the rigidity of the connection.
U.S. Pat. No. 1,101,810 describes a fastening system which also has the disadvantage that a lateral movement of the mucous membrane-supported denture is not possible. In this older suggestion, a sphere-shaped spring clip is embedded in the denture and covers a full sphere fastened in a tooth root by a pin. A further disadvantage of the full sphere is that the sphere projects far into the mouth cavity and the denture therefore has a greater tilting gradient. A further disadvantage, as in other prior art disclosures, is that a closure of an opening arranged in the jaw is not possible with a full sphere and, e.g., an end plate must be employed for closing a tooth root opening.
It has also been attempted to provide improved supports for removable tooth substitutes, such as, e.g., lower jaw dentures, with the help of implants or links inserted in the jaw ridge, the removable tooth substitutes being fastened on round or angular implant posts projecting from the jaw ridge. However, these attempts were not too successful, in particular, in the treatment of toothless lower jaws. The reasons for this are as follows: As a consequence of advanced atrophy in the lateral portion of the jaw bone, extremely unpleasant anatomical relations arise so that the insertion of implants in this area is seldom considered. Consequently, it is primarily the regio interforaminalis of the lower jaw that is available for implantations. When implants inserted in this area and connected with links are employed for supporting a lower jaw denture, a more or less rigid connection results.
Due to the resiliency of the lateral mucous membrane, a constant tilting load occurs during chewing and talking. The higher the implant posts project from the jaw bone, the more the tilting load increases. Consequently, the denture is not sufficiently secure and the denture wearer has a constant feeling of insecurity. This is because in the phase of the last closing movement, the lower jaw, as is known, carries out a vertical and horizontal movement which ends in a rotational movement. The previously known implantation systems or the removable tooth substitute attached to the implant, respectively, could not follow this movement without a defective loading occurring, in particular, with divergently inserted implant posts.